In preparation to ACPI support in Tegra fuse driver add function
tegra_acpi_init_apbmisc() to initialize tegra-apbmisc driver.
Also, document the reason of calling tegra_init_apbmisc() at early init.

Note that function tegra_acpi_init_apbmisc() is not placed in the __init
section, because it will be called during probe.

Signed-off-by: Kartik <kkar...@nvidia.com>
---
v2 -> v3:
        * Fix build warnings seen when CONFIG_ACPI is disabled by moving
          tegra_init_apbmisc table inside #ifdef CONFIG_ACPI block.

v1 -> v2:
        * Update ACPI ID table 'tegra_init_apbmisc'.
        * Add comment to document the reason to call tegra_init_apbmisc
          at early init.
        * Fix an issue where acpi_dev_free_resource_list() and
        * acpi_dev_put() were not called if
          acpi_dev_get_memory_resources() returned 1.
        * Update logic to fetch memory resources in
          tegra_acpi_init_apbmisc().
        * Fix build errors seen when CONFIG_ACPI is disabled.
---
 drivers/soc/tegra/fuse/fuse.h          |  1 +
 drivers/soc/tegra/fuse/tegra-apbmisc.c | 72 ++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/drivers/soc/tegra/fuse/fuse.h b/drivers/soc/tegra/fuse/fuse.h
index 90f23be73894..a41e9f85281a 100644
--- a/drivers/soc/tegra/fuse/fuse.h
+++ b/drivers/soc/tegra/fuse/fuse.h
@@ -69,6 +69,7 @@ struct tegra_fuse {
 
 void tegra_init_revision(void);
 void tegra_init_apbmisc(void);
+void tegra_acpi_init_apbmisc(void);
 
 u32 __init tegra_fuse_read_spare(unsigned int spare);
 u32 __init tegra_fuse_read_early(unsigned int offset);
diff --git a/drivers/soc/tegra/fuse/tegra-apbmisc.c 
b/drivers/soc/tegra/fuse/tegra-apbmisc.c
index 06c1b3a2c7ec..e2ca93de6c1f 100644
--- a/drivers/soc/tegra/fuse/tegra-apbmisc.c
+++ b/drivers/soc/tegra/fuse/tegra-apbmisc.c
@@ -3,9 +3,11 @@
  * Copyright (c) 2014-2023, NVIDIA CORPORATION.  All rights reserved.
  */
 
+#include <linux/acpi.h>
 #include <linux/export.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 
@@ -180,6 +182,12 @@ static void tegra_init_apbmisc_resources(struct resource 
*apbmisc,
        }
 }
 
+/**
+ * tegra_init_apbmisc - Initializes Tegra APBMISC and Strapping registers.
+ *
+ * This is called during early init as some of the old 32-bit ARM code needs
+ * information from the APBMISC registers very early during boot.
+ */
 void __init tegra_init_apbmisc(void)
 {
        struct resource apbmisc, straps;
@@ -244,3 +252,67 @@ void __init tegra_init_apbmisc(void)
 put:
        of_node_put(np);
 }
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id apbmisc_acpi_match[] = {
+       { "NVDA2010" },
+       { /* sentinel */ }
+};
+
+void tegra_acpi_init_apbmisc(void)
+{
+       struct resource *resources[2] = { NULL };
+       struct resource_entry *rentry, *tmp;
+       struct acpi_device *adev = NULL;
+       struct list_head resource_list;
+       int rcount = 0;
+       int ret;
+
+       adev = acpi_dev_get_first_match_dev(apbmisc_acpi_match[0].id, NULL, -1);
+       if (!adev)
+               return;
+
+       INIT_LIST_HEAD(&resource_list);
+
+       ret = acpi_dev_get_memory_resources(adev, &resource_list);
+       if (ret < 0) {
+               pr_err("failed to get APBMISC memory resources");
+               goto out_put_acpi_dev;
+       }
+
+       /*
+        * Get required memory resources.
+        *
+        * resources[0]: apbmisc.
+        * resources[1]: straps.
+        */
+       resource_list_for_each_entry_safe(rentry, tmp, &resource_list) {
+               if (rcount >= ARRAY_SIZE(resources))
+                       break;
+
+               resources[rcount++] = rentry->res;
+       }
+
+       if (!resources[0]) {
+               pr_err("failed to get APBMISC registers\n");
+               goto out_free_resource_list;
+       }
+
+       if (!resources[1]) {
+               pr_err("failed to get strapping options registers\n");
+               goto out_free_resource_list;
+       }
+
+       tegra_init_apbmisc_resources(resources[0], resources[1]);
+
+out_free_resource_list:
+       acpi_dev_free_resource_list(&resource_list);
+
+out_put_acpi_dev:
+       acpi_dev_put(adev);
+}
+#else
+void tegra_acpi_init_apbmisc(void)
+{
+}
+#endif
-- 
2.34.1


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